1. Field of the Invention
The present invention relates to a heating apparatus for false twisting of synthetic fiber which is used for false twisting a filament of thermoplastic synthetic fiber such as polyester or polyamide.
2. Description of Related Art
Conventional heat treatment apparatuses for false twisting of a filament of thermoplastic synthetic fiber are usually divided into contact type heating apparatuses and non-contact type high-temperature heating apparatuses.
Most contact type heating apparatuses employ a heating method which uses saturated vapor as the heat medium. Recently, high-speed processing and energy savings have been demanded in order to improve processing efficiency. However, the following problems prevent such demands from being satisfied.
To achieve high-speed processing, an enlarged heater is needed so that the resistance which a running filament encounters increases. The height of a false twister is enlarged so that a tall building is required to accommodate the apparatus, and thus maintenance is difficult to perform. As regards energy saving, stains on the surface in which a filament contacts increase thereby requiring procedures for cleaning. Thus, energy savings are difficult to achieve. Additionally, the availability of the apparatus is reduced because it is necessary to cease its operation for cleaning.
The non-contact type high-temperature heating apparatus is preferable for achieving false twisting capable of high-speed processing and saving energy. In such an apparatus, a groove-like passage through which a filament passes is formed by cutting the outside face of a long, heat-conductive, bar shaped material, such as a brass alloy (so-called brass), and a heating member is provided within the passage. By feeding a filament through the above mentioned passage, the filament is heated at a high temperature and a false twist of the filament is fixed.
However, the above non-contact type high-temperature heating apparatus has the following problems. One of the problems is that it is difficult to form a long groove and a heating member accommodating section axially on a bar-shaped metal such as a long brass alloy by cutting. As to the type of metal employed, if a heat resisting alloy, for example, inconel or a brass alloy, is used, it is further difficult to process the long groove and the heating member accommodating section because of the high degree of hardness, thereby leading to an increase in the manufacturing cost.